. Properties of genetic material The experiment by Hershey and Chase clearly indicates that it is DNA that acts as a genetic material. However, in some viruses like Tobacco mosaic virus (TMV), bacteriophage θB, RNA acts as the genetic material. A molecule that can act as a genetic material should have the following properties: • Self Replication: It should be able to replicate.
According to the rule of base pairing and complementarity, both nucleic acids (DNA and RNA) have the ability to components of adjacent nucleotides are called phosphodiester bond ( ' '), indicating the polarity of the strand. The ends of the DNA or RNA are distinct. The two ends are designated by the symbols ' and '. The symbol ' refers to carbon in the sugar to which a phosphate (PO ) functional group is attached.
The symbol ' refers to carbon in the sugar to which hydroxyl (OH) functional group is attached. In RNA, every nucleotide residue has an additional – OH group at ' position in the ribose. Understanding the ' ' direction of a nucleic acid is critical for understanding the aspects of replication and transcription. Based on the X - ray diffraction analysis of Maurice Wilkins and Rosalind Franklin , the double helix model for DNA was proposed by James Watson and Francis Crick in .
The highlight was the base pairing between the two strands of the polynucleotide chain. This proposition was based on the observations of Erwin Chargaff that Adenine pairs with Thymine (A = T) with two hydrogen bonds and Guanine pairs with Cytosine (G ≡ C) with three hydrogen bonds. The ratios between Adenine with Thymine and Guanine with Cytosine are constant and equal. The base pairing confers a unique property to the polynucleotide chain.
They are said to be complementary to each other, that is, if the sequence of bases in one strand (template) is known, then the sequence in the other strand can be predicted. The salient features of DNA structure has already been dealt in class XI.